Pain Case of the Month: Zachary—

Learn about multimodal pain management for a black-handed spider monkey, our first case involving a nonhuman primate.

Zachary, a male black-handed spider monkey.

A radiograph showing Zachary’s humerus.

by Mary Ellen Goldberg, LVT, CVT, SRA, CCRVN, CVPP, VTS (Lab Animal Medicine [Research Anesthesia]), VTS (Physical Rehabilitation), VTS-H (Anesthesia/Analgesia)

Introduction

Controlling pain is an important component to improving the welfare of captive animals. Zoo animals create unique challenges for the veterinary staff. These animals look different, have different social systems, and react to pain and pain medications differently than their domestic-species counterparts.

A zoo animal presents a special challenge compared with a household pet. Husbandry staff are trained to read subtle changes in the behavior, gait, or appearance of an animal. They will sound the alarm as soon as an animal begins to act uncharacteristically by utilizing their knowledge of the normal behavior of that animal or species. The entire team needs to be part of any treatment plan so that the responsibility of the animal’s daily care does not rest on one person.

Signalment and History

Zachary is a male Ateles geoffroyi (black-handed spider monkey) born on July 29, 1981. He was living at a zoological park under routine veterinary care until October 19, 2008, when keepers reported a swelling on his right elbow. Visual inspection showed an approximately three-centimeter-diameter mass on the caudal aspect of the right front cubital joint. He held his right arm at an angle rather than fully extending it but would use the affected limb for climbing and general ambulation.

Upon examination, it was discovered that the cubital joint was luxated with crepitus present. Radiographs showed that there was a possible condylar fracture of the right humerus and degenerative joint disease. The distal humerus was completely luxated dorsolaterally. Cytology of a synovial sample from the right cubital mass indicated sterile mild chronic synovitis with hemorrhage, suggesting pathologic fracture to previous ongoing degenerative disease process of right cubital joint.

On November 8, a visiting member of the American College of Veterinary Surgeons offered the following diagnosis: “Completely unstable right elbow joint on palpation with surrounding soft-tissue swelling. Radiographs indicate a humeral condylar fracture (right) lateral. Will likely require surgical repair: fracture reduction versus arthrodesis due to time since injury, age of animal, and size of bone.” A soft padded bandage was placed to provide mild support.

On January 25, 2009, the visiting surgeon plated the elbow. Humeral condyles were noted as nonexistent along with the radial head. Because of severe cubital joint degeneration, it was suspected that the patient had bilateral elbow dysplasia. Overall, the surgery was a success, although there was some concern expressed by the surgeon because of the brittle nature of the bone and the appearance of a hairline crack along the distal aspect of the humerus. The best chance for bone healing was to place a bandage that would immobilize the cubital and proximal glenoid joint for up to four weeks to allow the bones enough time to heal.

On February 24, the elbow started to arthrodese and there was no laxity in the humerus. Radiographs were taken that showed new bone formation around the cubital joint site.

On March 31, the elbow was continuing to arthrodese, but there was laxity and crepitus just proximal to the plate. Radiographs were taken that showed new bone formation around the proximal plate site. Lytic lesions were noted in the distal humeral area of the callus and proximal radial area; these lesions suggested that arthrodesis was not occurring sufficiently, probably because of instability.

On April 14, there was still palpable laxity and crepitus noted around the elbow (distal and proximal to the plate). Radiographs were taken that showed new bone formation around the proximal plate site. Radiographs appeared the same as previous images, with lytic lesions noted in the distal humeral area of callus and proximal radial area. Also noted were lytic areas around the screws in the humerus.

On December 29, the keeper reported that Zachary was having slight difficulty handling food with his left hand when it was given in the catch cage.

Presenting Signs (Chronic)

Because of chronic disuse of the right arm and now complete dislocation of the left arm, options are limited. Zach is mostly bipedal, though he still uses the left arm to swing and prehend food. He appears awkward when doing so, but it does not have the outward appearance of being painful. Radiographs of the right elbow show lytic lesions around the distal screws in the ulna, the third screw (counting from proximal to distal) is no longer attached to any bone, and the two most proximal screws are still present in the distal humerus, which has moderate to severe sclerosis. Radiographs of the left elbow show the humeral condyles to be completely absent, and there is no bony connection to the antebrachium.

Figure 1: Modified Cincinnati Orthopedic Disability Index for a Nonhuman Primate.

Figure 2: Scoring system for assessing mobility and locomotion for Zachary.

Choice of Therapy Including Drug and Nondrug

This certified veterinary pain practitioner suggested the following therapies to the team of veterinarians, veterinary technicians, and husbandry staff:

  • Long-term pharmacological therapy was initiated in April 2011, followed by physical rehabilitation methods and acupuncture.
  • Pharmacological therapy consisted of mixing tablets and capsules in fruits, vegetables, and treats that the nonhuman primate readily accepted (Table 1).
  • Nondrug therapy included laser therapy (Table 2) and physical rehabilitation (Table 3), as well as acupuncture treatment, which was applied once weekly, not under sedation, with operant conditioning (Table 4).

To avoid losing the acupuncture needles in the enclosure, if the animal moved from his targeted position at the front mesh, dental floss was tied around each acupuncture needle that was placed. This practice ensured that the needles would pull free from the skin and stay with the veterinarian administering the acupuncture treatment if the animal pulled away from the front of the enclosure.

Table 1. Pharmacologic Therapy

Medication Dosage How Administered Frequency Duration of Therapy
Gabapentin supplied in 10/100/600 mg tablets 10–20 mg/kg Orally mixed with food/treats Twice daily Until directed to stop
Glucosamine HCl 1,500 mg + chondroitin sulfate 350 mg capsule 1 capsule Orally mixed with food/treats Twice daily Until directed to stop
Omega-3 fatty acids capsules 1 capsule Orally mixed with food/treats Twice daily Until directed to stop
Meloxicam tablets 0.1–0.2 mg/kg Orally mixed with food/treats Once daily 1 month
Polysulfated Glycosaminoglycan 4.4 mg/kg Intramuscular Injection Twice Weekly For 4 weeks, then subcutaneously
every month and adjust frequency
according to patient needs

Table 2. Laser Therapy

Model Dosage Area Covered Frequency Duration of Therapy
Therapeutic laser 4–8 joules/cm2 Humeral condyles of both right and left limbs Once daily for 7 days, decreased to every other day during week 2 Applied on an as-needed basis

Table 3. Physical Rehabilitation Therapy

Manual Therapy Massage Techniques Hand Weights Therapy/Medicine Balls
Passive range of motion under sedation Effleurage and petrissage under sedation 1–2-pound Weider, neoprene covered, usage through mimicry Small physioball and 2-pound medicine ball Playing catch and throw back
Active range of motion through mimicry First and second week only 3 times weekly for 4 weeks 3 times weekly for 4 weeks

Table 4. Acupuncture Treatment for Elbow Pain Through a Certified Veterinary TCVM Acupuncture Veterinarian

Location Qi-Blood Stagnation Kidney Yang Deficiency Kidney Yin and Qi (or Yang) Deficiency Local Points,
Elbow Area
Acupuncture points TH-10, SI-8, Zhou-shu, Yan-zhou, Cheng-deng, SI-3, LI-4, LI-1, TH-1, TH-3 Bai-hui, Jian-jiao, BL-23, BL-11, BL-40, BL-60, GB-34, GB-39 KID-3, KID-10, BL-23, BL-26, Shen-shu, Shen-peng, Shen-jiao, LIV-3, SP-6, SP-9, ST-36, LI-10, LI-11 LI-10, LI-11, LU-5, TH-10, SI-8, HT-3, Zhou-shu (elbow associate)
  Bony bi syndrome Combine with local points Combine with local points  

Outcome

This male spider monkey is now using his right and left arms to prehend food, and he will use his right arm (in conjunction with his prehensile tail) to hang on to trees and enrichment objects. Each day, when the animal keepers feed him, it is noted in the record if he is observed using his limbs, along with medication administration. If not observed, then the veterinary staff is notified. With maintenance therapy, the spider monkey utilizes arm and hand movements daily for feeding and play.

Conclusion

The treatment plan provided allowed the veterinary staff and animal keepers to improve the spider monkey’s chronic pain without compromising his quality of life. Charts for assessment of mobility, locomotion, and adapted disability index were instituted (Figures 1 and 2), and these were developed by the certified veterinary pain practitioner. There are no known validated pain scales for nonhuman primates. This nonhuman primate continues to function as a happy member of his troop. He maintains a good quality of life while enjoying his conspecifics.

Discussion by Mike Petty, DVM, CCRT, CVPP, DAAPM

When I worked with Trends to set up the Pain Case of the Month, I made a promise to myself that I would not put in cases of exotics that would only be useful to less than 1% of the readers. But this is such an interesting case, and other than the unique problems that arise in the case of a primate, this case could easily be about a dog or a cat. The same issues are confronted and addressed: surgical intervention, follow-up exams and radiographs, and the eventual change to long-term chronic pain management.

Mike Petty, DVM, CCRT, CVPP, DAAPM, is in private practice in Canton, Michigan. He is a frequent national and international lecturer on topics related to pain management. Petty offers commentary on each Pain Case of the Month.

 

Mary Ellen Goldberg, LVT, CVT, SRA, CCRVN, CVPP, VTS (Lab Animal Medicine [Research Anesthesia]), VTS (Physical Rehabilitation), VTS-H (Anesthesia/Analgesia), is a graduate of Harcum College and the University of Pennsylvania (1976). Goldberg was chosen as the National Association of Veterinary Technicians in America’s Veterinary Technician of the Year in 2017. In November 2019, she received the VTS (Anesthesia/Analgesia) honorary title from the Academy of Veterinary Technicians in Anesthesia and Analgesia. She has written several books and contributed to numerous chapters on anesthesia, pain management, and rehabilitation.

 

Photo credits: Photos courtesy of Mary Ellen Goldberg

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